Field of the Invention
The invention concerns a female quick-connect coupling element for joining two pressurised-fluid pipes. The invention also concerns a quick-connect coupling comprising such a female element.
In the field of high-pressure fluid couplings, in particular suitable for the transfer of hydrogen, for which the pressure of the fluid may be around 800 bar, protecting the coupling by preventing the disconnection of a male element and female element when the pressure of the fluid is too high is known. This is because the whiplash that may occur when the pressure is high, at the time of disconnection, is hazardous to the operator manipulating the coupling.
To do this, the use is known, in particular from EP-A-1 745 237, of a piston moved radially by the pressure of the fluid flowing in the coupling to a locking position, in which a locking ring is locked in the locked position. When the locking ring is in position before locking and the male element is locked in the coupled position in the female element, for example by means of locking balls, release of the coupling is impossible since a rod of the piston projecting out of the body of the female element prevents movement of the locking ring to its release position. When the pressure of the fluid flowing in the coupling drops below a predetermined pressure level, a spring mounted in the same housing as the piston retracts the piston so that the locking means can once again be moved into the release position and the coupling can be decoupled without danger to the operator.
Similar devices, in which a spring is housed in the same housing as the piston, are also known from US-A-2009/243286 and US-A-2013/174928.
Brief Description of the Related Art
This type of construction has several drawbacks. Because of the small space available for the spring in the piston housing, it is difficult to guarantee a substantially constant return force over the compression travel of the spring. This drawback proves to be a problem when the locking and release pressures must be equivalent. Furthermore, when the piston locks the locking ring, if the operator seeks to actuate the locking ring, the piston is acted on under flexion, which may cause a leakage at the piston seal because of its short length.